摘要
光敏化反应为当前日趋活跃的研究领域,在探讨光敏化反应机理时,经常涉及到分子受激发后的状态变化及能量传递等重要过程。70年代以来,激光闪光光解技术已广泛地用于观测光化学反应中各种瞬态光谱及其变化的情况,为研究和探讨反应机理提供了新的途径。
The photosensitized triplet behaviours of benzophenone (BP) and energy transfer
from BP to naphthylalkanes (1, 3-di(2-naphthyl) propane, DNP, 1, 3-di (2'-naphthyl)
propyl-acetate, DNPA, (2-naphthyl) methyl acetate, NMA) was studied by nanosecond
laser flash photolysis in benzene solution.
After deoxygenation, the BP solution is excited with 355nm laser pulse, its T_1→T_n
absorption band appeared around 530nm with a decay time (triplet lifetime) of about
2.7μs. None of the three naphthylalkanes can be excited with the 355nm laser light
directly. After BP is added, besides T_1→T_n absorption band of BP, the new T_1→T_n
absorption bands of naphthyl-alkanes appeare between 400nm to 440nm; the absorption
maxima appear at 430nm (DNP),430nm (DNPA), and 422nm (NMA) respectively. The
T_1→T_n absorption of naphthylalkanes increased following the queuching of the
T_1→T_n absorption of BP and the triplet lifetime of BP is decreased dramatically. In these
photosensitized process, the triplet energy transfer efficiency (f_T) and transfer constant
(K_T) had been calculated (Table 1 and Table 2 of the Chinese text).
Compared with the T_1→T_n absorption of naphthalene (about 420nm) and the UV
spectrum, it was found that the T_1→T_n absorption bands and the UV spectra of
naphthylalkanes are similar to that of naphthalene and are red shifted. We believe that
the electron of the naphthalene ring can be excited to the triplet state only, after they
received the energy from BP. In addition, the molecular structure also affect the energy
levels of the excited state. Thus the acetoxy groupin DNPA or NMA showed steric
hindrance effect on the molecular collision. It may decrease the energy transfer rate
and efficiency.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
1989年第2期199-203,共5页
Acta Chimica Sinica
